In a power semiconductor element used at a high voltage exceeding several hundreds of volts (V), an insulating film is formed under the edge of a front-side electrode for electrical insulation between the front-side electrode and a back-side electrode each serving as a main electrode. Further, in the power semiconductor element, an electrode edge insulating protective film made of a resin material is formed to surround the outer periphery of the front-side electrode. On the power semiconductor element, an interconnection electrically connectable to the outside is formed, and thereafter the semiconductor element is sealed with a sealing resin. Accordingly, a semiconductor device is completed.
In such a semiconductor device, heat generated from the semiconductor element in operation causes a thermal stress between components of the semiconductor device, due to a difference in thermal expansion coefficient between materials forming the semiconductor device or due to cure shrinkage of the sealing resin.
As a result of this, a peeling defect may occur for example to the interface between a semiconductor substrate and the insulating film or the interface between the semiconductor substrate and the sealing resin. The peeling defect deteriorates the reliability of the semiconductor device and thus should be suppressed.
In the conventional semiconductor device, the region to be sealed with the sealing resin (epoxy resin for example) is entirely covered with a resin material (polyamide for example) having a uniform film thickness, to enhance the adhesive force between the sealing resin and internal components such as power semiconductor chip.